Attachment plug with locking device



July '14, 1936. s. E. FELTS 2,047,623

ATTACHMENT PLUG WITH LOCKING DEVICE Filed July 1, 1935 ATTORNEY UNITED STATES PATENT OFFICE ATTACHMENT PLUG wrrn LOCKING nsvron Samuel E. Felts, Pomona, CaliL, assignor of onehalf to Herman Felts, Calif.

San Bernardlno County.

Application July 1, 1935, Serial No. 29,413 2 Claims. (01.173-361) This invention relates to electrical plug caps 01' the type used with plugs that screw into sockets or used with floor or wall outlets direct. In plug caps of this type, as ordinarily used, the plug cap frequently becomes loosened causing considerable annoyance on the part of the person using an electrical circuit which is completed through the plug cap.

It is a primary object therei'ore of this inven- 10 tion to produce a plug cap which may be positively locked to or detached from standard floor or wall outlets, or any conventional type of attachment plug.

A further object is to provide a locking member 5 which is slidably supported on one of the contact prongs "and is provided with backwardly urned teeth adapted to penetrate either metal or composition materials and positively prevent inadvertent disengagement.

A further object is to provide releasing means which are associated with the locking member I and may be easily operated to release the locking member and permit removal or the plug cap from the plug or outlet.

A further object is to provide a plug cap formed of a few, simple, strong, durable and inexpensive parts which are easy to manufacture and which will not easily get out of order.

With the above and other objects in view the 30 invention consists of certain novel details of construction and combinations of parts hereinafter fully described and claimed, it being understood that various modifications may be resorted to within the scope of the appended claims without 35 departing from the spirit or sacrificing any of the advantages of the invention.

In the accompanying drawing forming part of this specification;

Figure 1 is a longitudinal sectional view oi. "a 40 plug cap constructed in accordance with my invention and showingvthe parts of the plug cap in locked position.

Figure 2 is a view similar to Figure 1 but showing the parts of the plug cap in unlocked position. 45 Figure 3 is a crosssectional view through the plug cap.

Figure 4 is a in Figure 3.

Figure 5 is a detail perspective view of one of 50 the prongs showing a flange thereon having an obliquely disposed guide slot.

Referring now to the drawing in which like charac ers of reference designate similar parts it the various views, the plug cap is shown to comprise similar sections in and II forming a top plan view or the parts shown hollow body, there being lugs l2 formed on the inner faces of the sections and counterbored to receive a bolt i3 for securing the sections together. The sections are provided with the usual flared nipple M for receiving the electric cord i5. 5 A pair of contact prongs i6 and H are secured to the body and receive the exposed ends I8 and I 9 of the conductor cord 95 through which the electric circuit completed by the plug cap is adapted to flow. The contact prong i6 is pro- 10 vided with a lug 20 to which the exposed end I 8 of the conductor cord is attachedby a screw M. A screw 2| is passed through the prong and into the body to rigidly anchor the prong to the body. The contact prong H, as best shown in Figure 5, is provided with a lug 22 through which a screw 23 is passed to secure the exposed end l9 0! the conductor cord to the contact prong.- Moreover this contact prong is provided with a flange 24 at the bottom which is provided with an ofiset 25 which forms a guideway or groove 26 which extends obliquely with respect to the axis of the body. The edge H of the contact prong is a continuation of the obliquely disposed inner wall 28 oi! the groove and coacts therewith 25 in forming a guide surface which extends obliquely to the axis of the body. The flange 24 is provided with 9. lug 29 having an opening 30 therein to receive a pivot pin 3|. The flange is also provided with an opening which receives a screw 33 for attaching the contact prong to the body. The offset 25 is engaged in a similar shaped recess in the body, as best shown in Figure 4, and coacts with the screw 33 in rigidly securing the prong to the body.

. A locking member 35 01' wedge shape, is slidably mounted on the guide surface 21 of the contact prong I! and is slidably received in the guide groove 26 formed in the flange of the contact prong. The outer edge of the locking member is provided with rearwardly extending serrations or teeth 36 adapted to penetrate the composition material of for instance the prong receiving slot in a conventional plug 31 when the locking member is slid outwardly to the locked position shown in Figure 1, and prevent accidental or inadvertent disengagement of the locking member. The teeth moreover will penetrate the metal lining sometimes found in floor and wall outlets and prevent dislodgment of the locking member.

A button 31 is mounted on the above mentioned pivot pin 3| and is provided with a radial slot 38 which receives a pin 39 that projects laterally 55 from the lower end of the locking member 88 and constitutes a lever assembly to impart movement to the locking member 35. A coil spring 8 is seated on the securing lugs l2 0! the body sections and exerts pressure on the button in a direction to urge the locking member 35 outwardly to locked position. The button 31' is accessible from the exterior of the body through a slot 4| and is provided with a knurled shoulder 42 diametrically opposite the slot38 which is exposed through the slot 4| in the body and permits of. the button being rocked counterclockwise to move the locking member 35 against the tension oi! the spring 0 and disengage the member from locked position.

From the above description it will be noted that the contact prongs l6 and I! and locking member 35 forming a component part of theprong ll, may be universally used with all conventional types of plugs and outlets and require no special fittings whatsoever.

What is claimed is:

1. An electrical plug cap comprising a hollow body formed oi sections provided with bolt receiving lugs for assembling the sections. contact prongs on the body. a locking member slidable longitudinally of one of the prongs, a spring seated on said lugs and urging the locking member outwardly, a projection on 'theslocking member, and a button accessible externally o! the body and having a radial slot receiving the projection for moving the locking member against the tension of the spring.

2. An electrical plug cap comprising a body. contact prongs on the body, a locking member slidable longitudinally of one of the prongs, a I

projection on the locking member, and a spring pressed button movable relatively to the locking member and accessible externally of the body and having means engaging the projection for imparting movement to the locking member.

8 E. FELTS. 

